全文获取类型
收费全文 | 11778篇 |
免费 | 574篇 |
国内免费 | 463篇 |
专业分类
电工技术 | 745篇 |
综合类 | 266篇 |
化学工业 | 2223篇 |
金属工艺 | 1384篇 |
机械仪表 | 1004篇 |
建筑科学 | 162篇 |
矿业工程 | 608篇 |
能源动力 | 198篇 |
轻工业 | 316篇 |
水利工程 | 19篇 |
石油天然气 | 111篇 |
武器工业 | 35篇 |
无线电 | 876篇 |
一般工业技术 | 2457篇 |
冶金工业 | 940篇 |
原子能技术 | 304篇 |
自动化技术 | 1167篇 |
出版年
2024年 | 30篇 |
2023年 | 211篇 |
2022年 | 497篇 |
2021年 | 510篇 |
2020年 | 358篇 |
2019年 | 301篇 |
2018年 | 320篇 |
2017年 | 400篇 |
2016年 | 388篇 |
2015年 | 356篇 |
2014年 | 573篇 |
2013年 | 606篇 |
2012年 | 541篇 |
2011年 | 950篇 |
2010年 | 621篇 |
2009年 | 711篇 |
2008年 | 633篇 |
2007年 | 614篇 |
2006年 | 595篇 |
2005年 | 577篇 |
2004年 | 498篇 |
2003年 | 394篇 |
2002年 | 356篇 |
2001年 | 262篇 |
2000年 | 232篇 |
1999年 | 199篇 |
1998年 | 183篇 |
1997年 | 151篇 |
1996年 | 118篇 |
1995年 | 115篇 |
1994年 | 126篇 |
1993年 | 81篇 |
1992年 | 45篇 |
1991年 | 39篇 |
1990年 | 33篇 |
1989年 | 26篇 |
1988年 | 33篇 |
1987年 | 20篇 |
1986年 | 10篇 |
1985年 | 17篇 |
1984年 | 8篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1966年 | 5篇 |
1965年 | 5篇 |
1964年 | 6篇 |
1960年 | 5篇 |
1958年 | 4篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 27 毫秒
101.
Glenn Melissa J.; Lehmann Hugo; Mumby Dave G.; Woodside Barbara 《Canadian Metallurgical Quarterly》2005,119(3):806
The authors explored the possibility that there are different neural consequences, beyond the primary site of brain damage, following perirhinal cortex (PRh) lesions made in different ways. Fos expression was used as a marker for neuronal activation and compared across the forebrains of rats that underwent the different types of surgery. Electrolytic and excitotoxic PRh lesions produced dramatic increases in Fos expression in the cortex, and excitotoxic and aspiration PRh lesions increased Fos expression in the dentate gyrus. These data are consistent with the hypothesis that different lesion methods have separable effects on neural function in regions outside the lesion site that could account for inconsistencies in the literature regarding the behavioral effects of PRh lesions on tests of spatial memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
102.
Schopp Laura H.; Johnstone Brick; Reid-Arndt Stephanie 《Canadian Metallurgical Quarterly》2005,36(2):158
Rural psychologists are frontline primary behavioral health care providers for nearly 60 million Americans, but they face limited access to peer consultation and continuing education. This article describes a program that matched 70 rehabilitation inpatients who had new brain injury with rural clinicians from patients' home communities. Neuropsychologists provided one-on-one training for clinicians through telehealth video teleconferencing. Clinicians showed gains in brain injury knowledge, and clients rated trained providers higher than untrained providers. Families seeking brain injury services can connect with these trained rural providers through a Web site, which receives more than 800 hits per month. Telehealth offers potential for rural clinicians to receive support, reduce professional isolation, gain working knowledge of specialty conditions, and deliver high-quality services for their rural clients. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
104.
A. Nikolic Lj. Petrov Dj. Koruga S. Mihajlovic 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,13(1):53-59
Magnetic behavior of C60 thin films in the Earth's magnetic field under polarization light influence is presented. Transformation of magnetic field for two fullerene thin films of different thickness is investigated. Two proton magnetometers were used for these measurements. Samples of 30 nm and 250 nm thickness illustrate a significant change of magnetic field intensity under the influence of polarization light, in range from 3.4 to 12.9 nT, for 200 measurement data per sample. 相似文献
105.
It has become of paramount importance to be able to perform failure analysis of defects on hard disk surfaces quickly and accurately. In this study, ultrasonic pitting defects on hard disk surfaces were investigated. A new electrical tagging pattern system, which directly translated the channel bits to magnetic transitions during writing of the magnetic pattern around a defect, was used in the failure analysis of magnetic recording disks to mark defective sectors. With the help of the Kerr magneto-effect, the defective sectors were effectively located for further failure analysis. Results of the failure analysis revealed that there was 30% to 40% loss of the recorded magnetic bit signal due to an increase in the gap between a recording head and a hard disk surface with ultrasonic pitting defects. The experiments performed indicated that low ultrasonic power for disk cleaning could reduce the ultrasonic pitting defects significantly. The maximum failure rate due to single-type ultrasonic pitting defects was reduced from 33.4% to 16.7%, while the maximum failure rate due to cluster-type ultrasonic pitting defects was reduced from 11.1% to 5%. 相似文献
106.
Feng Li 《Materials Research Bulletin》2005,40(8):1244-1255
In this paper, a series of pure Ni1 − xZnxFe2O4 (0 ≤ x ≤ 1) spinel ferrites have been synthesized successfully using a novel route through calcination of tailored hydrotalcite-like layered double hydroxide molecular precursors of the type [(Ni + Zn)1 − x − yFey2+Fex3+(OH)2]x+(SO42−)x/2·mH2O at 900 °C for 2 h, in which the molar ratio of (Ni2+ + Zn2+)/(Fe2+ + Fe3+) was adjusted to the same value as that in single spinel ferrite itself. The physico-chemical characteristics of the LDHs and their resulting calcined products were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy. The results indicate that calcination of the as-synthesized LDH precursor affords a pure single Ni1 − xZnxFe2O4 (0 ≤ x ≤ 1) spinel ferrite phase. Moreover, formation of pure ferrites starting from LDHs precursors requires a much lower temperature and shorter time, leading to a lower chance of side-reactions occurring, because all metal cations on the brucite-like layers of LDHs can be uniformly distributed at an atomic level. 相似文献
107.
108.
Farhad Shir Catherine Mavriplis Lawrence H. Bennett Edward Della Torre 《International Journal of Refrigeration》2005,28(4):1082
Results of a room temperature magnetic refrigeration test bed and an analysis using a computational model are presented. A detailed demonstration of the four sequential processes in the transient magnetocaloric regeneration process of a magnetic material is presented. The temperature profile during the transient approach to steady state operation was measured in detail. A 5 °C evolution of the difference of temperature between the hot end and the cold end of the magnetocaloric bed due to regeneration is reported. A model is developed for the heat transfer and fluid mechanics of the four sequential processes in each cycle of thermal wave propagation in the regenerative bed combined with the magnetocaloric effect. The basic equations that can be used in simulation of magnetic refrigeration systems are derived and the design parameters are discussed. 相似文献
109.
α-Fe(NiCoAl) solid-solution nanocapsules were prepared with pure powders of Fe, Ni, Co and Al by the plasma arc-discharging using a copper crucible. The shapes of the nanocapsules are in polyhedrons with the core/shell structure. The body centered cubic (BCC) phase is formed in the core. The size of the nanocapsules is in the range of 10~120 nm and the thickness of the shell is 4~11 nm. Saturation magnetization Js=150 Am2/kg and coercivity iHC=24.3 kA/m are achieved for the nanocapsules. 相似文献
110.
A single-stage G-M type pulse tube cooler (PTC) was designed and tested to explore the lowest attainable refrigeration temperature and to further improve the cooling performance in the temperature range of 15-40 K. The magnetic material Er3Ni was used as part of the regenerative material besides the phosphor-bronze and the lead so as to improve the efficiency of the regenerator. With an input power of 6 kW, a lowest no-load refrigeration temperature of 12.6 K was obtained, which is a new record for the single-stage PTC. The cooling capacity at 15-40 K was also significantly improved, which may extend the application of the single-stage PTC for the cooling of superconductors and cryopumps. 相似文献